1. Field of the Invention
This invention relates to vehicle window drive system and method and, more particularly, to a multi-tooth contact drive gear system and method used in a vehicle window environment which may be manufactured using roll manufacturing techniques.
2. Description of Related Art
In window drive systems of the past, it was not uncommon to use a worm gear which was rotatably driven by a drive motor and which, in turn, drove a driven gear. Typically, the worm gear comprised a torque capacity which was much less than, for example, an enveloped gear. This was due primarily to the fact that the worm gear had a primary or single contact tooth which contacted a mating tooth of the driven gear.
Unfortunately, to achieve multi-tooth contact and increased torque capacity and other advantages of an enveloped gear, the teeth of the enveloped gear had to be specially machined and could not typically be mass-produced using conventional roll manufacturing techniques.
In the past, attempts have been made to use conventional roll manufacturing techniques to generate a multi-contact worm gear; however, such designs were deficient because the contact points (where the gear teeth of the drive gear contacted mating teeth of the driven gear) were situated on an arc which was concentric about the axis of the driven gear. This had the disadvantage of causing the multiple teeth to contact the driven teeth at a single contact location on the driven gear. This, in turn, increased the wear at that contact point, thereby reducing the useful life of the driven gear.
What is needed, therefore, is a system and method for providing a drive gear which will have improved torque capacity and which can be manufactured on a mass production basis using roll manufacturing techniques.